Power couples don't get that way by accident. Devotion to mission and a tireless work ethic go down a lot easier when both members of a pair approach their jobs the same way. That kind of stick-to-the-flight-plan determination was on display Friday afternoon when NASA and astronaut Mark Kelly  husband of injured Congresswoman Gabrielle Giffords  convened a news conference at the Johnson Space Center in Houston to announce that Kelly would be in the commander's seat as planned when the shuttle Endeavour takes off in April.

Kelly, 46, has flown in space three times before, but this time was going to be special. It would be both his and Endeavour's final mission  and perhaps the last of the shuttle program as a whole if money isn't forthcoming for one more flight later in the year. What's more, the objective of the mission is to deliver the alpha magnetic spectrometer (AMS) to the International Space Station. The AMS will be affixed to the station's truss and will try to collect particle evidence of the cosmos' little understood dark matter and dark energy, which are thought to serve as nothing less than the mortar that holds the universe together. (See pictures of the labor of space exploration.)

But those plans  at least Kelly's role in them  were blown to bits last month when Giffords was shot in the head at an outdoor constituent event, landing her in an intensive-care unit and, more recently, a long-term rehab facility. "Four weeks ago tomorrow, I was sitting in the ICU in Tuscon and talking to her neurosurgeon and trauma surgeon about her progress," Kelly said today. "At that time I thought I'd likely be sitting in that same seat maybe two, four, six months later."

But if he were there today, he'd be very lonely. On Jan. 21  way ahead of schedule  Giffords had recovered sufficiently to be moved to the Memorial Hermann Rehabilitation Hospital in Houston, handily close to the space center, where Kelly trains. (See pictures of Tucson in grief over the Giffords shooting.)

Even then, there was little thought in his mind that he would fly the two-week mission  and little in NASA's plans either. The famously risk-averse space agency wants nothing to do with any astronaut  least of all a commander  whose mind isn't fully on the job. Said Peggy Whitson, head of the NASA astronaut office: "We weren't going to ask him to command if he didn't want to. I have to choose a crew that will be able to support the mission."

All that changed in the past couple of weeks, mostly because of Giffords. The optimistic press releases about the speed of her improvement are more than sunny spin. Her doctors place her recovery in the one-percentile category, impressive enough that since her arrival in Houston she's been putting in the equivalent of a full workday  from 8 a.m. to 6 p.m.  working on speech, motor control, strength and more.

That left Kelly with little to do, and so two weeks ago, he approached Whitson and Brent Jett, director of flight-crew operations, about rejoining his crew. There were a few things that worked in his favor. His launch date had twice slipped for technical reasons  from February to early April and then again to April 19. This would allow him to catch up on any preparations he'd missed.

What's more, NASA tries to keep its crew decisions as free of emotion as it can, which means that everything comes down to safety. Kelly had logged 18 months of training, far more than his backup commander had. Provided he could prove he was fully focused on the mission, the flight would be his. To reassure himself that his mind would indeed be clear, he canvassed his family to see if they approved.

"When I told [Giffords' mother] in the ICU in Houston that I would most likely not be flying, she said, 'What, are you kidding me? You have to go and do that,' " Kelly says. He got the same response from Giffords' father.

The question that reporters kept asking today was what Giffords herself said, or even if she is yet capable of speaking at all. Kelly was polite but adamant that he would not disclose any details about her recovery, except to say whether she is gaining or losing ground, and he stuck to that. "I know her very well," was pretty much all he said.

Among those journalists present was ABC's Bob Woodruff, who knows better than anyone in the room what Giffords is going through, having suffered his own devastating head and brain trauma as the result of an IED explosion in Iraq in 2006. Woodruff asked Kelly if he would see Giffords face to face during the two weeks he's aloft, courtesy of the video-conference equipment that's available in orbit.

"Typically, we do one family video conference during a mission, toward the end of the flight," Kelly answered. "So this time we'll do that too."

"One time?" Woodruff pressed. "In 14 days?"

"Yes, one time," Kelly answered.

That, for both Kelly and Giffords, may well be enough. He has a mission to perform during those two weeks, and so does she. They'll both be more than busy enough, thank you very much.